opencode: add OAC

opencode/context/development/backend-navigation.md

@@ -0,0 +1,79 @@
+<!-- Context: development/navigation | Priority: low | Version: 1.0 | Updated: 2026-02-15 -->
+
+# Backend Development Navigation
+
+**Scope**: Server-side, APIs, databases, auth
+
+---
+
+## Structure
+
+```
+development/backend/           # [future]
+├── navigation.md
+│
+├── api-patterns/              # Approach-based
+│   ├── rest-design.md
+│   ├── graphql-design.md
+│   ├── grpc-patterns.md
+│   └── websocket-patterns.md
+│
+├── nodejs/                    # Tech-specific
+│   ├── express-patterns.md
+│   ├── fastify-patterns.md
+│   └── error-handling.md
+│
+├── python/
+│   ├── fastapi-patterns.md
+│   └── django-patterns.md
+│
+├── authentication/            # Functional concern
+│   ├── jwt-patterns.md
+│   ├── oauth-patterns.md
+│   └── session-management.md
+│
+└── middleware/
+    ├── logging.md
+    ├── rate-limiting.md
+    └── cors.md
+```
+
+---
+
+## Quick Routes
+
+| Task | Path |
+|------|------|
+| **REST API** | `backend/api-patterns/rest-design.md` [future] |
+| **GraphQL** | `backend/api-patterns/graphql-design.md` [future] |
+| **API design principles** | `principles/api-design.md` |
+| **Node.js** | `backend/nodejs/express-patterns.md` [future] |
+| **Python** | `backend/python/fastapi-patterns.md` [future] |
+| **Auth (JWT)** | `backend/authentication/jwt-patterns.md` [future] |
+
+---
+
+## By Approach
+
+**REST** → `backend/api-patterns/rest-design.md` [future]
+**GraphQL** → `backend/api-patterns/graphql-design.md` [future]
+**gRPC** → `backend/api-patterns/grpc-patterns.md` [future]
+
+## By Language
+
+**Node.js** → `backend/nodejs/` [future]
+**Python** → `backend/python/` [future]
+
+## By Concern
+
+**Authentication** → `backend/authentication/` [future]
+**Middleware** → `backend/middleware/` [future]
+**Data layer** → `data/` [future]
+
+---
+
+## Related Context
+
+- **API Design Principles** → `principles/api-design.md`
+- **Core Standards** → `../core/standards/code-quality.md`
+- **Data Patterns** → `data/navigation.md` [future]